101
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Hakim V, Ranft J. Lifetime of a structure evolving by cluster aggregation and particle loss, and application to postsynaptic scaffold domains. Phys Rev E 2020; 101:012411. [PMID: 32069640 DOI: 10.1103/physreve.101.012411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 01/21/2023]
Abstract
The dynamics of several mesoscopic biological structures depend on the interplay of growth through the incorporation of components of different sizes laterally diffusing along the cell membrane, and loss by component turnover. In particular, a model of such an out-of-equilibrium dynamics has recently been proposed for postsynaptic scaffold domains, which are key structures of neuronal synapses. It is of interest to estimate the lifetime of these mesoscopic structures, especially in the context of synapses where this time is related to memory retention. The lifetime of a structure can be very long as compared to the turnover time of its components and it can be difficult to estimate it by direct numerical simulations. Here, in the context of the model proposed for postsynaptic scaffold domains, we approximate the aggregation-turnover dynamics by a shot-noise process. This enables us to analytically compute the quasistationary distribution describing the sizes of the surviving structures as well as their characteristic lifetime. We show that our analytical estimate agrees with numerical simulations of a full spatial model, in a regime of parameters where a direct assessment is computationally feasible. We then use our approach to estimate the lifetime of mesoscopic structures in parameter regimes where computer simulations would be prohibitively long. For gephyrin, the scaffolding protein specific to inhibitory synapses, we estimate a lifetime longer than several months for a scaffold domain when the single gephyrin protein turnover time is about half an hour, as experimentally measured. While our focus is on postsynaptic domains, our formalism and techniques should be applicable to other biological structures that are also formed by a balance of condensation and turnover.
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Affiliation(s)
- Vincent Hakim
- Laboratoire de Physique de l'Ecole Normale Supérieure, CNRS, Ecole Normale Supérieure, PSL University, Sorbonne Université, Université Paris-Diderot, Paris, France
| | - Jonas Ranft
- Institut de Biologie de l'ENS (IBENS), Ecole Normale Supérieure, PSL University, CNRS, INSERM, Paris, France
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102
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Park CE, Cho Y, Cho I, Jung H, Kim B, Shin JH, Choi S, Kwon SK, Hahn YK, Chang JB. Super-Resolution Three-Dimensional Imaging of Actin Filaments in Cultured Cells and the Brain via Expansion Microscopy. ACS NANO 2020; 14:14999-15010. [PMID: 33095573 DOI: 10.1021/acsnano.0c04915] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Actin is an essential protein in almost all life forms. It mediates diverse biological functions, ranging from controlling the shape of cells and cell movements to cargo transport and the formation of synaptic connections. Multiple diseases are closely related to the dysfunction of actin or actin-related proteins. Despite the biological importance of actin, super-resolution imaging of it in tissue is still challenging, as it forms very dense networks in almost all cells inside the tissue. In this work, we demonstrate multiplexed super-resolution volumetric imaging of actin in both cultured cells and mouse brain slices via expansion microscopy (ExM). By introducing a simple labeling process, which enables the anchoring of an actin probe, phalloidin, to a swellable hydrogel, the multiplexed ExM imaging of actin filaments was achieved. We first showed that this technique could visualize the nanoscale details of actin filament organizations in cultured cells. Then, we applied this technique to mouse brain slices and visualized diverse actin organizations, such as the parallel actin filaments along the long axis of dendrites and dense actin structures in postsynaptic spines. We examined the postsynaptic spines in the mouse brain and showed that the organizations of actin filaments are highly diverse. This technique, which enables the high-throughput 60 nm resolution imaging of actin filaments and other proteins in cultured cells and thick tissue slices, would be a useful tool to study the organization of actin filaments in diverse biological circumstances and how they change under pathological conditions.
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Affiliation(s)
- Chan E Park
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Youngbin Cho
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - In Cho
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Hyunsu Jung
- Division of Life Sciences, Korea University, Seoul 02841, Korea
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Byeongyeon Kim
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Korea
| | - Jennifer H Shin
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Sungyoung Choi
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Korea
| | - Seok-Kyu Kwon
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea
- Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Seoul 02792, Korea
| | - Young Ki Hahn
- Biomedical Convergence Science & Technology, Industrial Technology Advances, Kyungpook National University, Daegu 41566, Korea
| | - Jae-Byum Chang
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- KI for Health Science and Technology, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
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103
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Wiesner T, Bilodeau A, Bernatchez R, Deschênes A, Raulier B, De Koninck P, Lavoie-Cardinal F. Activity-Dependent Remodeling of Synaptic Protein Organization Revealed by High Throughput Analysis of STED Nanoscopy Images. Front Neural Circuits 2020; 14:57. [PMID: 33177994 PMCID: PMC7594516 DOI: 10.3389/fncir.2020.00057] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 07/29/2020] [Indexed: 01/03/2023] Open
Abstract
The organization of proteins in the apposed nanodomains of pre- and postsynaptic compartments is thought to play a pivotal role in synaptic strength and plasticity. As such, the alignment between pre- and postsynaptic proteins may regulate, for example, the rate of presynaptic release or the strength of postsynaptic signaling. However, the analysis of these structures has mainly been restricted to subsets of synapses, providing a limited view of the diversity of synaptic protein cluster remodeling during synaptic plasticity. To characterize changes in the organization of synaptic nanodomains during synaptic plasticity over a large population of synapses, we combined STimulated Emission Depletion (STED) nanoscopy with a Python-based statistical object distance analysis (pySODA), in dissociated cultured hippocampal circuits exposed to treatments driving different forms of synaptic plasticity. The nanoscale organization, characterized in terms of coupling properties, of presynaptic (Bassoon, RIM1/2) and postsynaptic (PSD95, Homer1c) scaffold proteins was differently altered in response to plasticity-inducing stimuli. For the Bassoon - PSD95 pair, treatments driving synaptic potentiation caused an increase in their coupling probability, whereas a stimulus driving synaptic depression had an opposite effect. To enrich the characterization of the synaptic cluster remodeling at the population level, we applied unsupervised machine learning approaches to include selected morphological features into a multidimensional analysis. This combined analysis revealed a large diversity of synaptic protein cluster subtypes exhibiting differential activity-dependent remodeling, yet with common features depending on the expected direction of plasticity. The expanded palette of synaptic features revealed by our unbiased approach should provide a basis to further explore the widely diverse molecular mechanisms of synaptic plasticity.
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Affiliation(s)
| | | | | | | | | | - Paul De Koninck
- CERVO Brain Research Centre, Québec, QC, Canada.,Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Québec, QC, Canada
| | - Flavie Lavoie-Cardinal
- CERVO Brain Research Centre, Québec, QC, Canada.,Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada
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104
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Parra-Damas A, Saura CA. Tissue Clearing and Expansion Methods for Imaging Brain Pathology in Neurodegeneration: From Circuits to Synapses and Beyond. Front Neurosci 2020; 14:914. [PMID: 33122983 PMCID: PMC7571329 DOI: 10.3389/fnins.2020.00914] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 08/07/2020] [Indexed: 11/30/2022] Open
Abstract
Studying the structural alterations occurring during diseases of the nervous system requires imaging heterogeneous cell populations at the circuit, cellular and subcellular levels. Recent advancements in brain tissue clearing and expansion methods allow unprecedented detailed imaging of the nervous system through its entire scale, from circuits to synapses, including neurovascular and brain lymphatics elements. Here, we review the state-of-the-art of brain tissue clearing and expansion methods, mentioning their main advantages and limitations, and suggest their parallel implementation for circuits-to-synapses brain imaging using conventional (diffraction-limited) light microscopy -such as confocal, two-photon and light-sheet microscopy- to interrogate the cellular and molecular basis of neurodegenerative diseases. We discuss recent studies in which clearing and expansion methods have been successfully applied to study neuropathological processes in mouse models and postmortem human brain tissue. Volumetric imaging of cleared intact mouse brains and large human brain samples has allowed unbiased assessment of neuropathological hallmarks. In contrast, nanoscale imaging of expanded cells and brain tissue has been used to study the effect of protein aggregates on specific subcellular structures. Therefore, these approaches can be readily applied to study a wide range of brain processes and pathological mechanisms with cellular and subcellular resolution in a time- and cost-efficient manner. We consider that a broader implementation of these technologies is necessary to reveal the full landscape of cellular and molecular mechanisms underlying neurodegenerative diseases.
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Affiliation(s)
- Arnaldo Parra-Damas
- Institut de Neurociències, Departament de Bioquímica i Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain
| | - Carlos A Saura
- Institut de Neurociències, Departament de Bioquímica i Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, Madrid, Spain
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105
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Synaptic vesicles transiently dock to refill release sites. Nat Neurosci 2020; 23:1329-1338. [PMID: 32989294 PMCID: PMC8054220 DOI: 10.1038/s41593-020-00716-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 09/01/2020] [Indexed: 11/18/2022]
Abstract
Synaptic vesicles fuse with the plasma membrane to release neurotransmitter following an action potential, after which new vesicles must ‘dock’ to refill vacated release sites. To capture synaptic vesicle exocytosis at cultured mouse hippocampal synapses, we induced single action potentials by electrical field stimulation then subjected neurons to high-pressure freezing to examine their morphology by electron microscopy. During synchronous release, multiple vesicles can fuse at a single active zone. Fusions during synchronous release are distributed throughout the active zone, whereas fusions during asynchronous release are biased toward the center of the active zone. After stimulation, the total number of docked vesicles across all synapses decreases by ~40%. Within 14 ms, new vesicles are recruited and fully replenish the docked pool, but this docking is transient and they either undock or fuse within 100 ms. These results demonstrate that recruitment of synaptic vesicles to release sites is rapid and reversible.
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106
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Suratkal SS, Yen YH, Nishiyama J. Imaging dendritic spines: molecular organization and signaling for plasticity. Curr Opin Neurobiol 2020; 67:66-74. [PMID: 32942126 DOI: 10.1016/j.conb.2020.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 08/08/2020] [Accepted: 08/10/2020] [Indexed: 12/26/2022]
Abstract
The structural plasticity of dendritic spines is considered to be essential for various forms of synaptic plasticity and, ultimately, learning and memory. The process is mediated by signaling pathways that promote the reorganization of the actin cytoskeleton and subsynaptic structures, which in turn cause structural and functional changes in dendritic spines. Recent advances in optical technologies have started to reveal the fine molecular structures and dynamic signaling occurring inside spines, providing significant insights into the molecular regulation of spines. Here, we highlight recent studies to resolve the molecular mechanisms underlying the spine actin cytoskeleton and plasticity with high spatiotemporal resolution. Moreover, we discuss new genome editing-based approaches in imaging the molecular structure and plasticity of dendritic spines.
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Affiliation(s)
- Swathi Shivaram Suratkal
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Yu-Hsin Yen
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Jun Nishiyama
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore.
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107
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Distance-dependent regulation of NMDAR nanoscale organization along hippocampal neuron dendrites. Proc Natl Acad Sci U S A 2020; 117:24526-24533. [PMID: 32929031 PMCID: PMC7533699 DOI: 10.1073/pnas.1922477117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Hippocampal pyramidal neurons are characterized by a unique arborization subdivided in segregated dendritic domains receiving distinct excitatory synaptic inputs with specific properties and plasticity rules that shape their respective contributions to synaptic integration and action potential firing. Although the basal regulation and plastic range of proximal and distal synapses are known to be different, the composition and nanoscale organization of key synaptic proteins at these inputs remains largely elusive. Here we used superresolution imaging and single nanoparticle tracking in rat hippocampal neurons to unveil the nanoscale topography of native GluN2A- and GluN2B-NMDA receptors (NMDARs)-which play key roles in the use-dependent adaptation of glutamatergic synapses-along the dendritic arbor. We report significant changes in the nanoscale organization of GluN2B-NMDARs between proximal and distal dendritic segments, whereas the topography of GluN2A-NMDARs remains similar along the dendritic tree. Remarkably, the nanoscale organization of GluN2B-NMDARs at proximal segments depends on their interaction with calcium/calmodulin-dependent protein kinase II (CaMKII), which is not the case at distal segments. Collectively, our data reveal that the nanoscale organization of NMDARs changes along dendritic segments in a subtype-specific manner and is shaped by the interplay with CaMKII at proximal dendritic segments, shedding light on our understanding of the functional diversity of hippocampal glutamatergic synapses.
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108
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Huebschman JL, Corona KS, Guo Y, Smith LN. The Fragile X Mental Retardation Protein Regulates Striatal Medium Spiny Neuron Synapse Density and Dendritic Spine Morphology. Front Mol Neurosci 2020; 13:161. [PMID: 33013316 PMCID: PMC7511717 DOI: 10.3389/fnmol.2020.00161] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/05/2020] [Indexed: 01/23/2023] Open
Abstract
The fragile X mental retardation protein (FMRP), an RNA-binding protein that mediates the transport, stability, and translation of hundreds of brain RNAs, is critically involved in regulating synaptic function. Loss of FMRP, as in fragile X syndrome (FXS), is a leading monogenic cause of autism and results in altered structural and functional synaptic plasticity, widely described in the hippocampus and cortex. Though FXS is associated with hyperactivity, impaired social interaction, and the development of repetitive or stereotyped behaviors, all of which are influenced by striatal activity, few studies have investigated the function of FMRP here. Utilizing a cortical-striatal co-culture model, we find that striatal medium spiny neurons (MSNs) lacking FMRP fail to make normal increases in PSD95 expression over a short time period and have significant deficits in dendritic spine density and colocalized synaptic puncta at the later measured time point compared to wildtype (WT) MSNs. Acute expression of wtFMRP plasmid in Fmr1 KO co-cultures results in contrasting outcomes for these measures on MSNs at the more mature time point, reducing spine density across multiple spine types but making no significant changes in colocalized puncta. FMRP’s KH2 and RGG RNA-binding domains are required for normal elimination of PSD95, and interruption of these domains slightly favors elimination of immature spine types. Further, KH2 is required for normal levels of colocalized puncta. Our data are largely consistent with a basal role for FMRP and its RNA-binding domains in striatal synapse stabilization on developing MSNs, and in light of previous findings, suggest distinct regional and/or cell type-specific roles for FMRP in regulating synapse structure.
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Affiliation(s)
- Jessica L Huebschman
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States.,Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, United States
| | - Kitzia S Corona
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Yuhong Guo
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Laura N Smith
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center, Bryan, TX, United States.,Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, United States
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109
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Zhang H, Bramham CR. Arc/Arg3.1 function in long-term synaptic plasticity: Emerging mechanisms and unresolved issues. Eur J Neurosci 2020; 54:6696-6712. [PMID: 32888346 DOI: 10.1111/ejn.14958] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 07/18/2020] [Accepted: 08/14/2020] [Indexed: 02/06/2023]
Abstract
Arc (activity-regulated cytoskeleton-associated protein) is posited as a critical regulator of long-term synaptic plasticity at excitatory synapses, including long-term potentiation, long-term depression, inverse synaptic tagging and homoeostatic scaling, with pivotal roles in memory and postnatal cortical development. However, the mechanisms underlying the bidirectional regulation of synaptic strength are poorly understood. Here we review evidence from different plasticity paradigms, highlight outstanding issues and discuss stimulus-specific mechanisms that dictate Arc function. We propose a model in which Arc bidirectionally controls synaptic strength by coordinate regulation of AMPA-type glutamate receptor (AMPAR) trafficking and actin cytoskeletal dynamics in dendritic spines. Key to this model, Arc is proposed to function as an activity-dependent regulator of AMPAR lateral membrane diffusion and trapping at synapses.
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Affiliation(s)
- Hongyu Zhang
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Clive R Bramham
- Department of Biomedicine, University of Bergen, Bergen, Norway
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110
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McLeod F, Boyle K, Marzo A, Martin-Flores N, Moe TZ, Palomer E, Gibb AJ, Salinas PC. Wnt Signaling Through Nitric Oxide Synthase Promotes the Formation of Multi-Innervated Spines. Front Synaptic Neurosci 2020; 12:575863. [PMID: 33013349 PMCID: PMC7509412 DOI: 10.3389/fnsyn.2020.575863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/13/2020] [Indexed: 01/06/2023] Open
Abstract
Structural plasticity of synapses correlates with changes in synaptic strength. Dynamic modifications in dendritic spine number and size are crucial for long-term potentiation (LTP), the cellular correlate of learning and memory. Recent studies have suggested the generation of multi-innervated spines (MIS), in the form of several excitatory presynaptic inputs onto one spine, are crucial for hippocampal memory storage. However, little is known about the molecular mechanisms underlying MIS formation and their contribution to LTP. Using 3D enhanced resolution confocal images, we examined the contribution of Wnt synaptic modulators in MIS formation in the context of LTP. We show that blockage of endogenous Wnts with specific Wnt antagonists supresses the formation of MIS upon chemical LTP induction in cultured hippocampal neurons. Gain- and loss-of-function studies demonstrate that Wnt7a signaling promotes MIS formation through the postsynaptic Wnt scaffold protein Disheveled 1 (Dvl1) by stimulating neuronal nitric oxide (NO) synthase (nNOS). Subsequently, NO activates soluble guanylyl cyclase (sGC) to increase MIS formation. Consistently, we observed an enhanced frequency and amplitude of excitatory postsynaptic currents. Collectively, our findings identify a unique role for Wnt secreted proteins through nNOS/NO/sGC signaling to modulate MIS formation during LTP.
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Affiliation(s)
- Faye McLeod
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Kieran Boyle
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Aude Marzo
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Nuria Martin-Flores
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Thaw Zin Moe
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Ernest Palomer
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Alasdair J Gibb
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Patricia C Salinas
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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111
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AMPA receptor nanoscale dynamic organization and synaptic plasticities. Curr Opin Neurobiol 2020; 63:137-145. [DOI: 10.1016/j.conb.2020.04.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/28/2020] [Accepted: 04/13/2020] [Indexed: 12/13/2022]
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112
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Kokolaki ML, Fauquier A, Renner M. Molecular Crowding and Diffusion-Capture in Synapses. iScience 2020; 23:101382. [PMID: 32739837 PMCID: PMC7399191 DOI: 10.1016/j.isci.2020.101382] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/23/2020] [Accepted: 07/14/2020] [Indexed: 12/17/2022] Open
Abstract
Cell membranes often contain domains with important physiological functions. A typical example are neuronal synapses, whose capacity to capture receptors for neurotransmitters is central to neuronal functions. Receptors diffuse in the membrane until they are stabilized by interactions with stable elements, the scaffold. Single particle tracking experiments demonstrated that these interactions are rather weak and that lateral diffusion is strongly impaired in the post-synaptic membrane due to molecular crowding. We investigated how the distribution of scaffolding molecules and molecular crowding affect the capture of receptors. In particle-based Monte Carlo simulations, based on experimental data of molecular diffusion and organization, crowding enhanced the receptor-scaffold interaction but reduced the capture of new molecules. The distribution of scaffolding sites in several clusters reduced crowding and fostered the exchange of molecules accelerating synaptic plasticity. Synapses could switch between two regimes, becoming more stable or more plastic depending on the internal distribution of molecules. The good: molecular crowding enhances the interaction receptors-scaffold The bad: the exchange of molecules with extrasynaptic areas is reduced by crowding Molecular crowding helps synapses to be stable Nanoclusters of scaffold sites reduce crowding effects and favor synaptic plasticity
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Affiliation(s)
| | - Aurélien Fauquier
- Sorbonne Université UMR-S 1270 INSERM, Institut du Fer à Moulin (IFM), 75005 Paris, France
| | - Marianne Renner
- Sorbonne Université UMR-S 1270 INSERM, Institut du Fer à Moulin (IFM), 75005 Paris, France.
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113
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Pizzarelli R, Griguoli M, Zacchi P, Petrini EM, Barberis A, Cattaneo A, Cherubini E. Tuning GABAergic Inhibition: Gephyrin Molecular Organization and Functions. Neuroscience 2020; 439:125-136. [PMID: 31356900 PMCID: PMC7351109 DOI: 10.1016/j.neuroscience.2019.07.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/16/2019] [Accepted: 07/17/2019] [Indexed: 01/15/2023]
Abstract
To be highly reliable, synaptic transmission needs postsynaptic receptors (Rs) in precise apposition to the presynaptic release sites. At inhibitory synapses, the postsynaptic protein gephyrin self-assembles to form a scaffold that anchors glycine and GABAARs to the cytoskeleton, thus ensuring the accurate accumulation of postsynaptic receptors at the right place. This protein undergoes several post-translational modifications which control protein-protein interaction and downstream signaling pathways. In addition, through the constant exchange of scaffolding elements and receptors in and out of synapses, gephyrin dynamically regulates synaptic strength and plasticity. The aim of the present review is to highlight recent findings on the functional role of gephyrin at GABAergic inhibitory synapses. We will discuss different approaches used to interfere with gephyrin in order to unveil its function. In addition, we will focus on the impact of gephyrin structure and distribution at the nanoscale level on the functional properties of inhibitory synapses as well as the implications of this scaffold protein in synaptic plasticity processes. Finally, we will emphasize how gephyrin genetic mutations or alterations in protein expression levels are implicated in several neuropathological disorders, including autism spectrum disorders, schizophrenia, temporal lobe epilepsy and Alzheimer's disease, all associated with severe deficits of GABAergic signaling. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Rocco Pizzarelli
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy
| | - Marilena Griguoli
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy
| | - Paola Zacchi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Enrica Maria Petrini
- Fondazione Istituto Italiano di Tecnologia (IIT), Department of Neuroscience and Brain Technologies, Plasticity of inhibitory networks Unit, Genoa, Italy
| | - Andrea Barberis
- Fondazione Istituto Italiano di Tecnologia (IIT), Department of Neuroscience and Brain Technologies, Plasticity of inhibitory networks Unit, Genoa, Italy
| | - Antonino Cattaneo
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy; Scuola Normale Superiore, Pisa, Italy
| | - Enrico Cherubini
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy; Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy.
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114
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Zheng P, Su QP, Jin D, Yu Y, Huang XF. Prevention of Neurite Spine Loss Induced by Dopamine D2 Receptor Overactivation in Striatal Neurons. Front Neurosci 2020; 14:642. [PMID: 32655360 PMCID: PMC7324769 DOI: 10.3389/fnins.2020.00642] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/25/2020] [Indexed: 11/22/2022] Open
Abstract
Psychosis has been considered a disorder of impaired neuronal connectivity. Evidence for excessive formation of dopamine D2 receptor (D2R) – disrupted in schizophrenia 1 (DISC1) complexes has led to a new perspective on molecular mechanisms involved in psychotic symptoms. Here, we investigated how excessive D2R–DISC1 complex formation induced by D2R agonist quinpirole affects neurite growth and dendritic spines in striatal neurons. Fluorescence resonance energy transfer (FRET), stochastic optical reconstruction microscopy (STORM), and cell penetrating-peptide delivery were used to study the cultured striatal neurons from mouse pups. Using these striatal neurons, our study showed that: (1) D2R interacted with DISC1 in dendritic spines, neurites and soma of cultured striatal neurons; (2) D2R and DISC1 complex accumulated in clusters in dendritic spines of striatal neurons and the number of the complex were reduced after application of TAT-D2pep; (3) uncoupling D2R–DISC1 complexes by TAT-D2pep protected neuronal morphology and dendritic spines; and (4) TAT-D2pep prevented neurite and dendritic spine loss, which was associated with restoration of expression levels of synaptophysin and PSD-95. In addition, we found that Neuropeptide Y (NPY) and GSK3β were involved in the protective effects of TAT-D2pep on the neurite spines of striatal spiny projection neurons. Thus, our results may offer a new strategy for precisely treating neurite spine deficits associated with schizophrenia.
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Affiliation(s)
- Peng Zheng
- Illawarra Health and Medical Research Institute (IHMRI) and School of Medicine, University of Wollongong, Wollongong, NSW, Australia
| | - Qian Peter Su
- Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
| | - Dayong Jin
- Institute for Biomedical Materials and Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
| | - Yinghua Yu
- Jiangsu Key Laboratory of Immunity and Metabolism, Xuzhou Medical University, Xuzhou, China
| | - Xu-Feng Huang
- Illawarra Health and Medical Research Institute (IHMRI) and School of Medicine, University of Wollongong, Wollongong, NSW, Australia
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115
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Harris KM. Structural LTP: from synaptogenesis to regulated synapse enlargement and clustering. Curr Opin Neurobiol 2020; 63:189-197. [PMID: 32659458 DOI: 10.1016/j.conb.2020.04.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/30/2020] [Indexed: 02/09/2023]
Abstract
Nature teaches us that form precedes function, yet structure and function are intertwined. Such is the case with synapse structure, function, and plasticity underlying learning, especially in the hippocampus, a crucial brain region for memory formation. As the hippocampus matures, enduring changes in synapse structure produced by long-term potentiation (LTP) shift from synaptogenesis to synapse enlargement that is homeostatically balanced by stalled spine outgrowth and local spine clustering. Production of LTP leads to silent spine outgrowth at P15, and silent synapse enlargement in adult hippocampus at 2hours, but not at 5 or 30min following induction. Here we consider structural LTP in the context of developmental stage and variation in the availability of local resources of endosomes, smooth endoplasmic reticulum and polyribosomes. The emerging evidence supports a need for more nuanced analysis of synaptic plasticity in the context of subcellular resource availability and developmental stage.
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116
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Nanoscale co-organization and coactivation of AMPAR, NMDAR, and mGluR at excitatory synapses. Proc Natl Acad Sci U S A 2020; 117:14503-14511. [PMID: 32513712 PMCID: PMC7321977 DOI: 10.1073/pnas.1922563117] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The nanoscale co-organization of neurotransmitter receptors facing presynaptic release sites is a fundamental determinant of their coactivation and of synaptic physiology. At excitatory synapses, how endogenous AMPARs, NMDARs, and mGluRs are co-organized inside the synapse and their respective activation during glutamate release are still unclear. Combining single-molecule superresolution microscopy, electrophysiology, and modeling, we determined the average quantity of each glutamate receptor type, their nanoscale organization, and their respective activation. We observed that NMDARs form a unique cluster mainly at the center of the PSD, while AMPARs segregate in clusters surrounding the NMDARs. mGluR5 presents a different organization and is homogenously dispersed at the synaptic surface. From these results, we build a model predicting the synaptic transmission properties of a unitary synapse, allowing better understanding of synaptic physiology.
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117
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Li Z, Wang Z, Pan J, Ma X, Zhang W, Ouyang Z. Single-Cell Mass Spectrometry Analysis of Metabolites Facilitated by Cell Electro-Migration and Electroporation. Anal Chem 2020; 92:10138-10144. [DOI: 10.1021/acs.analchem.0c02147] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Zishuai Li
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Zhengmao Wang
- MOE Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Junmin Pan
- MOE Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaoxiao Ma
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Wenpeng Zhang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Zheng Ouyang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
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118
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Held RG, Liu C, Ma K, Ramsey AM, Tarr TB, De Nola G, Wang SSH, Wang J, van den Maagdenberg AMJM, Schneider T, Sun J, Blanpied TA, Kaeser PS. Synapse and Active Zone Assembly in the Absence of Presynaptic Ca 2+ Channels and Ca 2+ Entry. Neuron 2020; 107:667-683.e9. [PMID: 32616470 DOI: 10.1016/j.neuron.2020.05.032] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 04/24/2020] [Accepted: 05/21/2020] [Indexed: 12/12/2022]
Abstract
Presynaptic CaV2 channels are essential for Ca2+-triggered exocytosis. In addition, there are two competing models for their roles in synapse structure. First, Ca2+ channels or Ca2+ entry may control synapse assembly. Second, active zone proteins may scaffold CaV2s to presynaptic release sites, and synapse structure is CaV2 independent. Here, we ablated all three CaV2s using conditional knockout in cultured hippocampal neurons or at the calyx of Held, which abolished evoked exocytosis. Compellingly, synapse and active zone structure, vesicle docking, and transsynaptic nano-organization were unimpaired. Similarly, long-term blockade of action potentials and Ca2+ entry did not disrupt active zone assembly. Although CaV2 knockout impaired the localization of β subunits, α2δ-1 localized normally. Rescue with CaV2 restored exocytosis, and CaV2 active zone targeting depended on the intracellular C-terminus. We conclude that synapse assembly is independent of CaV2s or Ca2+ entry through them. Instead, active zone proteins recruit and anchor CaV2s via CaV2 C-termini.
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Affiliation(s)
- Richard G Held
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Changliang Liu
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Kunpeng Ma
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing 100101, China
| | - Austin M Ramsey
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Tyler B Tarr
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Giovanni De Nola
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Shan Shan H Wang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jiexin Wang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Toni Schneider
- Institute for Neurophysiology, University of Cologne, Köln 50931, Germany
| | - Jianyuan Sun
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing 100101, China
| | - Thomas A Blanpied
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Pascal S Kaeser
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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119
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Abstract
Regulation of neurotransmitter receptor content at synapses is achieved through a dynamic equilibrium between biogenesis and degradation pathways, receptor stabilization at synaptic sites, and receptor trafficking in and out synapses. In the past 20 years, the movements of receptors to and from synapses have emerged as a series of highly regulated processes that mediate postsynaptic plasticity. Our understanding of the properties and roles of receptor movements has benefited from technological advances in receptor labeling and tracking capacities, as well as from new methods to interfere with their movements. Focusing on two key glutamatergic receptors, we review here our latest understanding of the characteristics of receptor movements and their role in tuning the efficacy of synaptic transmission in health and brain disease.
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Affiliation(s)
- Laurent Groc
- Interdisciplinary Institute for NeuroScience, CNRS, UMR 5297, Centre Broca Nouvelle-Aquitaine, 146, rue Léo-Saignat, 33076 Bordeaux, France
- IINS, University of Bordeaux, UMR5297, Bordeaux, France
| | - Daniel Choquet
- Interdisciplinary Institute for NeuroScience, CNRS, UMR 5297, Centre Broca Nouvelle-Aquitaine, 146, rue Léo-Saignat, 33076 Bordeaux, France
- IINS, University of Bordeaux, UMR5297, Bordeaux, France
- Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, Bordeaux, France
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120
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Radler MR, Suber A, Spiliotis ET. Spatial control of membrane traffic in neuronal dendrites. Mol Cell Neurosci 2020; 105:103492. [PMID: 32294508 PMCID: PMC7317674 DOI: 10.1016/j.mcn.2020.103492] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/24/2020] [Accepted: 04/01/2020] [Indexed: 02/06/2023] Open
Abstract
Neuronal dendrites are highly branched and specialized compartments with distinct structures and secretory organelles (e.g., spines, Golgi outposts), and a unique cytoskeletal organization that includes microtubules of mixed polarity. Dendritic membranes are enriched with proteins, which specialize in the formation and function of the post-synaptic membrane of the neuronal synapse. How these proteins partition preferentially in dendrites, and how they traffic in a manner that is spatiotemporally accurate and regulated by synaptic activity are long-standing questions of neuronal cell biology. Recent studies have shed new insights into the spatial control of dendritic membrane traffic, revealing new classes of proteins (e.g., septins) and cytoskeleton-based mechanisms with dendrite-specific functions. Here, we review these advances by revisiting the fundamental mechanisms that control membrane traffic at the levels of protein sorting and motor-driven transport on microtubules and actin filaments. Overall, dendrites possess unique mechanisms for the spatial control of membrane traffic, which might have specialized and co-evolved with their highly arborized morphology.
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Affiliation(s)
- Megan R Radler
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA
| | - Ayana Suber
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA.
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121
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Zaccard CR, Shapiro L, Martin-de-Saavedra MD, Pratt C, Myczek K, Song A, Forrest MP, Penzes P. Rapid 3D Enhanced Resolution Microscopy Reveals Diversity in Dendritic Spinule Dynamics, Regulation, and Function. Neuron 2020; 107:522-537.e6. [PMID: 32464088 DOI: 10.1016/j.neuron.2020.04.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 12/19/2019] [Accepted: 04/27/2020] [Indexed: 12/31/2022]
Abstract
Dendritic spinules are thin protrusions, formed by neuronal spines, not adequately resolved by diffraction-limited light microscopy, which has limited our understanding of their behavior. Here we performed rapid structured illumination microscopy and enhanced resolution confocal microscopy to study spatiotemporal spinule dynamics in cortical pyramidal neurons. Spinules recurred at the same locations on mushroom spine heads. Most were short-lived, dynamic, exploratory, and originated near simple PSDs, whereas a subset was long-lived, elongated, and associated with complex PSDs. These subtypes were differentially regulated by Ca2+ transients. Furthermore, the postsynaptic Rac1-GEF kalirin-7 regulated spinule formation, elongation, and recurrence. Long-lived spinules often contained PSD fragments, contacted distal presynaptic terminals, and formed secondary synapses. NMDAR activation increased spinule number, length, and contact with distal presynaptic elements. Spinule subsets, dynamics, and recurrence were validated in cortical neurons of acute brain slices. Thus, we identified unique properties, regulatory mechanisms, and functions of spinule subtypes, supporting roles in neuronal connectivity.
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Affiliation(s)
- Colleen R Zaccard
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA
| | - Lauren Shapiro
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA
| | | | - Christopher Pratt
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA
| | - Kristoffer Myczek
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA
| | - Amy Song
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA
| | - Marc P Forrest
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA
| | - Peter Penzes
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA; Department of Psychiatry and Behavioral Sciences, Northwestern University, Chicago, IL 60611, USA.
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122
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Nanostructural Diversity of Synapses in the Mammalian Spinal Cord. Sci Rep 2020; 10:8189. [PMID: 32424125 PMCID: PMC7235094 DOI: 10.1038/s41598-020-64874-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/21/2020] [Indexed: 11/25/2022] Open
Abstract
Functionally distinct synapses exhibit diverse and complex organisation at molecular and nanoscale levels. Synaptic diversity may be dependent on developmental stage, anatomical locus and the neural circuit within which synapses reside. Furthermore, astrocytes, which align with pre and post-synaptic structures to form ‘tripartite synapses’, can modulate neural circuits and impact on synaptic organisation. In this study, we aimed to determine which factors impact the diversity of excitatory synapses throughout the lumbar spinal cord. We used PSD95-eGFP mice, to visualise excitatory postsynaptic densities (PSDs) using high-resolution and super-resolution microscopy. We reveal a detailed and quantitative map of the features of excitatory synapses in the lumbar spinal cord, detailing synaptic diversity that is dependent on developmental stage, anatomical region and whether associated with VGLUT1 or VGLUT2 terminals. We report that PSDs are nanostructurally distinct between spinal laminae and across age groups. PSDs receiving VGLUT1 inputs also show enhanced nanostructural complexity compared with those receiving VGLUT2 inputs, suggesting pathway-specific diversity. Finally, we show that PSDs exhibit greater nanostructural complexity when part of tripartite synapses, and we provide evidence that astrocytic activation enhances PSD95 expression. Taken together, these results provide novel insights into the regulation and diversification of synapses across functionally distinct spinal regions and advance our general understanding of the ‘rules’ governing synaptic nanostructural organisation.
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123
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de Vivo L, Nagai H, De Wispelaere N, Spano GM, Marshall W, Bellesi M, Nemec KM, Schiereck SS, Nagai M, Tononi G, Cirelli C. Evidence for sleep-dependent synaptic renormalization in mouse pups. Sleep 2020; 42:5543176. [PMID: 31374117 PMCID: PMC6802737 DOI: 10.1093/sleep/zsz184] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 06/13/2019] [Indexed: 12/14/2022] Open
Abstract
In adolescent and adult brains several molecular, electrophysiological, and ultrastructural measures of synaptic strength are higher after wake than after sleep [1, 2]. These results support the proposal that a core function of sleep is to renormalize the increase in synaptic strength associated with ongoing learning during wake, to reestablish cellular homeostasis and avoid runaway potentiation, synaptic saturation, and memory interference [2, 3]. Before adolescence however, when the brain is still growing and many new synapses are forming, sleep is widely believed to promote synapse formation and growth. To assess the role of sleep on synapses early in life, we studied 2-week-old mouse pups (both sexes) whose brain is still undergoing significant developmental changes, but in which sleep and wake are easy to recognize. In two strains (CD-1, YFP-H) we found that pups spend ~50% of the day asleep and show an immediate increase in total sleep duration after a few hours of enforced wake, indicative of sleep homeostasis. In YFP-H pups we then used serial block-face electron microscopy to examine whether the axon-spine interface (ASI), an ultrastructural marker of synaptic strength, changes between wake and sleep. We found that the ASI of cortical synapses (layer 2, motor cortex) was on average 33.9% smaller after sleep relative to after extended wake and the differences between conditions were consistent with multiplicative scaling. Thus, the need for sleep-dependent synaptic renormalization may apply also to the young, pre-weaned cerebral cortex, at least in the superficial layers of the primary motor area.
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Affiliation(s)
- Luisa de Vivo
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
| | - Hirotaka Nagai
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
| | | | | | - William Marshall
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
| | - Michele Bellesi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
| | | | | | - Midori Nagai
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI
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124
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Xu F, Ma D, MacPherson KP, Liu S, Bu Y, Wang Y, Tang Y, Bi C, Kwok T, Chubykin AA, Yin P, Calve S, Landreth GE, Huang F. Three-dimensional nanoscopy of whole cells and tissues with in situ point spread function retrieval. Nat Methods 2020; 17:531-540. [PMID: 32371980 PMCID: PMC7289454 DOI: 10.1038/s41592-020-0816-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 03/19/2020] [Indexed: 02/07/2023]
Abstract
Single-molecule localization microscopy is a powerful tool for visualizing subcellular structures, interactions and protein functions in biological research. However, inhomogeneous refractive indices inside cells and tissues distort the fluorescent signal emitted from single-molecule probes, which rapidly degrades resolution with increasing depth. We propose a method that enables the construction of an in situ 3D response of single emitters directly from single-molecule blinking datasets, and therefore allows their locations to be pinpointed with precision that achieves the Cramér-Rao lower bound and uncompromised fidelity. We demonstrate this method, named in situ PSF retrieval (INSPR), across a range of cellular and tissue architectures, from mitochondrial networks and nuclear pores in mammalian cells to amyloid-β plaques and dendrites in brain tissues and elastic fibers in developing cartilage of mice. This advancement expands the routine applicability of super-resolution microscopy from selected cellular targets near coverslips to intra- and extracellular targets deep inside tissues.
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Affiliation(s)
- Fan Xu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Donghan Ma
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Kathryn P MacPherson
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Sheng Liu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Ye Bu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Yu Wang
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.,Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Yu Tang
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, USA
| | - Cheng Bi
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Tim Kwok
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - Alexander A Chubykin
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, USA
| | - Peng Yin
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.,Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Sarah Calve
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA.
| | - Gary E Landreth
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA. .,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Fang Huang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA. .,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, USA. .,Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA.
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125
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Crosby KC, Gookin SE, Garcia JD, Hahm KM, Dell'Acqua ML, Smith KR. Nanoscale Subsynaptic Domains Underlie the Organization of the Inhibitory Synapse. Cell Rep 2020; 26:3284-3297.e3. [PMID: 30893601 DOI: 10.1016/j.celrep.2019.02.070] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 01/03/2019] [Accepted: 02/19/2019] [Indexed: 12/15/2022] Open
Abstract
Inhibitory synapses mediate the majority of synaptic inhibition in the brain, thereby controlling neuronal excitability, firing, and plasticity. Although essential for neuronal function, the central question of how these synapses are organized at the subsynaptic level remains unanswered. Here, we use three-dimensional (3D) super-resolution microscopy to image key components of the inhibitory postsynaptic domain and presynaptic terminal, revealing that inhibitory synapses are organized into nanoscale subsynaptic domains (SSDs) of the gephyrin scaffold, GABAARs and the active-zone protein Rab3-interacting molecule (RIM). Gephyrin SSDs cluster GABAAR SSDs, demonstrating nanoscale architectural interdependence between scaffold and receptor. GABAAR SSDs strongly associate with active-zone RIM SSDs, indicating an important role for GABAAR nanoscale organization near sites of GABA release. Finally, we find that in response to elevated activity, synapse growth is mediated by an increase in the number of postsynaptic SSDs, suggesting a modular mechanism for increasing inhibitory synaptic strength.
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Affiliation(s)
- Kevin C Crosby
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Sara E Gookin
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Joshua D Garcia
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Katlin M Hahm
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Mark L Dell'Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Katharine R Smith
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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126
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Letellier M, Lagardère M, Tessier B, Janovjak H, Thoumine O. Optogenetic control of excitatory post-synaptic differentiation through neuroligin-1 tyrosine phosphorylation. eLife 2020; 9:e52027. [PMID: 32324534 PMCID: PMC7180054 DOI: 10.7554/elife.52027] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Abstract
Neuroligins (Nlgns) are adhesion proteins mediating trans-synaptic contacts in neurons. However, conflicting results around their role in synaptic differentiation arise from the various techniques used to manipulate Nlgn expression level. Orthogonally to these approaches, we triggered here the phosphorylation of endogenous Nlgn1 in CA1 mouse hippocampal neurons using a photoactivatable tyrosine kinase receptor (optoFGFR1). Light stimulation for 24 hr selectively increased dendritic spine density and AMPA-receptor-mediated EPSCs in wild-type neurons, but not in Nlgn1 knock-out neurons or when endogenous Nlgn1 was replaced by a non-phosphorylatable mutant (Y782F). Moreover, light stimulation of optoFGFR1 partially occluded LTP in a Nlgn1-dependent manner. Combined with computer simulations, our data support a model by which Nlgn1 tyrosine phosphorylation promotes the assembly of an excitatory post-synaptic scaffold that captures surface AMPA receptors. This optogenetic strategy highlights the impact of Nlgn1 intracellular signaling in synaptic differentiation and potentiation, while enabling an acute control of these mechanisms.
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Affiliation(s)
- Mathieu Letellier
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
- CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
| | - Matthieu Lagardère
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
- CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
| | - Béatrice Tessier
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
- CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
| | - Harald Janovjak
- Australian Regenerative Medicine Institute (ARMI), Faculty of Medicine, Nursing and Health Sciences, Monash UniversityClaytonAustralia
- European Molecular Biology Laboratory Australia (EMBL Australia), Monash UniversityClaytonAustralia
| | - Olivier Thoumine
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
- CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297BordeauxFrance
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127
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Sanderson TM, Georgiou J, Collingridge GL. Illuminating Relationships Between the Pre- and Post-synapse. Front Neural Circuits 2020; 14:9. [PMID: 32308573 PMCID: PMC7146027 DOI: 10.3389/fncir.2020.00009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 03/06/2020] [Indexed: 12/11/2022] Open
Abstract
Excitatory synapses in the mammalian cortex are highly diverse, both in terms of their structure and function. However, relationships between synaptic features indicate they are highly coordinated entities. Imaging techniques, that enable physiology at the resolution of individual synapses to be investigated, have allowed the presynaptic activity level of the synapse to be related to postsynaptic function. This approach has revealed that neuronal activity induces the pre- and post-synapse to be functionally correlated and that subsets of synapses are more susceptible to certain forms of synaptic plasticity. As presynaptic function is often examined in isolation from postsynaptic properties, the effect it has on the post-synapse is not fully understood. However, since postsynaptic receptors at excitatory synapses respond to release of glutamate, it follows that they may be differentially regulated depending on the frequency of its release. Therefore, examining postsynaptic properties in the context of presynaptic function may be a useful way to approach a broad range of questions on synaptic physiology. In this review, we focus on how optophysiology tools have been utilized to study relationships between the pre- and the post-synapse. Multiple imaging techniques have revealed correlations in synaptic properties from the submicron to the dendritic level. Optical tools together with advanced imaging techniques are ideally suited to illuminate this area further, due to the spatial resolution and control they allow.
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Affiliation(s)
| | - John Georgiou
- Lunenfeld-Tanenbaum Research Institute, Toronto, ON, Canada
| | - Graham L Collingridge
- Lunenfeld-Tanenbaum Research Institute, Toronto, ON, Canada.,Tanz Centre for Research in Neurodegenerative Diseases, Department of Physiology, University of Toronto, Toronto, ON, Canada.,Glutamate Research Group, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
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128
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Cirelli C, Tononi G. Effects of sleep and waking on the synaptic ultrastructure. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190235. [PMID: 32248785 PMCID: PMC7209920 DOI: 10.1098/rstb.2019.0235] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We summarize here several studies performed in our laboratory, mainly using serial block-face scanning electron microscopy (SBEM), to assess how sleep, spontaneous waking and short sleep deprivation affect the size and number of synapses in the cerebral cortex and hippocampus. With SBEM, we reconstructed thousands of cortical and hippocampal excitatory, axospinous synapses and compared the distribution of their size after several hours of sleep relative to several hours of waking. Because stronger synapses are on average also bigger, the goal was to test a prediction of the synaptic homeostasis hypothesis, according to which overall synaptic strength increases during waking, owing to ongoing learning, and needs to be renormalized during sleep, to avoid saturation and to benefit memory consolidation and integration. Consistent with this hypothesis, we found that the size of the axon–spine interface (ASI), a morphological measure of synaptic strength, was on average smaller after sleep, but with interesting differences between primary cortex and the CA1 region of the hippocampus. In two-week-old mouse pups, the decline in ASI size after sleep was larger, and affected more cortical synapses, compared with one-month-old adolescent mice, suggesting that synaptic renormalization during sleep may be especially important during early development. This work is still in progress and other brain areas need to be tested after sleep, acute sleep loss and chronic sleep restriction. Still, the current results show that a few hours of sleep or waking lead to significant changes in synaptic morphology that can be linked to changes in synaptic efficacy. This article is part of the Theo Murphy meeting issue ‘Memory reactivation: replaying events past, present and future’.
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Affiliation(s)
- Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Blvd, Madison, WI 53719, USA
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Blvd, Madison, WI 53719, USA
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129
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Structural Remodeling of Active Zones Is Associated with Synaptic Homeostasis. J Neurosci 2020; 40:2817-2827. [PMID: 32122953 DOI: 10.1523/jneurosci.2002-19.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 02/16/2020] [Accepted: 02/22/2020] [Indexed: 02/07/2023] Open
Abstract
Perturbations to postsynaptic glutamate receptors (GluRs) trigger retrograde signaling to precisely increase presynaptic neurotransmitter release, maintaining stable levels of synaptic strength, a process referred to as homeostatic regulation. However, the structural change of homeostatic regulation remains poorly defined. At wild-type Drosophila neuromuscular junction synapse, there is one Bruchpilot (Brp) ring detected by superresolution microscopy at active zones (AZs). In the present study, we report multiple Brp rings (i.e., multiple T-bars seen by electron microscopy) at AZs of both male and female larvae when GluRs are reduced. At GluRIIC-deficient neuromuscular junctions, quantal size was reduced but quantal content was increased, indicative of homeostatic presynaptic potentiation. Consistently, multiple Brp rings at AZs were observed in the two classic synaptic homeostasis models (i.e., GluRIIA mutant and pharmacological blockade of GluRIIA activity). Furthermore, postsynaptic overexpression of the cell adhesion protein Neuroligin 1 partially rescued multiple Brp rings phenotype. Our study thus supports that the formation of multiple Brp rings at AZs might be a structural basis for synaptic homeostasis.SIGNIFICANCE STATEMENT Synaptic homeostasis is a conserved fundamental mechanism to maintain efficient neurotransmission of neural networks. Active zones (AZs) are characterized by an electron-dense cytomatrix, which is largely composed of Bruchpilot (Brp) at the Drosophila neuromuscular junction synapses. It is not clear how the structure of AZs changes during homeostatic regulation. To address this question, we examined the structure of AZs by superresolution microscopy and electron microscopy during homeostatic regulation. Our results reveal multiple Brp rings at AZs of glutamate receptor-deficient neuromuscular junction synapses compared with single Brp ring at AZs in wild type (WT). We further show that Neuroligin 1-mediated retrograde signaling regulates multiple Brp ring formation at glutamate receptor-deficient synapses. This study thus reveals a regulatory mechanism for synaptic homeostasis.
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130
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Heine M, Holcman D. Asymmetry Between Pre- and Postsynaptic Transient Nanodomains Shapes Neuronal Communication. Trends Neurosci 2020; 43:182-196. [DOI: 10.1016/j.tins.2020.01.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/12/2020] [Accepted: 01/13/2020] [Indexed: 10/25/2022]
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131
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Optogenetic Control of Spine-Head JNK Reveals a Role in Dendritic Spine Regression. eNeuro 2020; 7:ENEURO.0303-19.2019. [PMID: 31937523 PMCID: PMC7053173 DOI: 10.1523/eneuro.0303-19.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 12/18/2019] [Accepted: 12/19/2019] [Indexed: 12/27/2022] Open
Abstract
In this study, we use an optogenetic inhibitor of c-Jun NH2-terminal kinase (JNK) in dendritic spine sub-compartments of rat hippocampal neurons. We show that JNK inhibition exerts rapid (within seconds) reorganization of actin in the spine-head. Using real-time Förster resonance energy transfer (FRET) to measure JNK activity, we find that either excitotoxic insult (NMDA) or endocrine stress (corticosterone), activate spine-head JNK causing internalization of AMPARs and spine retraction. Both events are prevented upon optogenetic inhibition of JNK, and rescued by JNK inhibition even 2 h after insult. Moreover, we identify that the fast-acting anti-depressant ketamine reduces JNK activity in hippocampal neurons suggesting that JNK inhibition may be a downstream mediator of its anti-depressant effect. In conclusion, we show that JNK activation plays a role in triggering spine elimination by NMDA or corticosterone stress, whereas inhibition of JNK facilitates regrowth of spines even in the continued presence of glucocorticoid. This identifies that JNK acts locally in the spine-head to promote AMPAR internalization and spine shrinkage following stress, and reveals a protective function for JNK inhibition in preventing spine regression.
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132
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Abstract
Current understanding of the neuroanatomical abnormalities in autism includes gross anatomical changes in several brain areas and microstructural alterations in neuronal cells as well. There are many controversies in the interpretation of the imaging data, evaluation of volume and size of particular brain areas, and their functional translation into a broad autism phenotype. Critical questions of neuronal pathology in autism include the concept of the reversible plasticity of morphological changes, volume alterations of brain areas, and both short- and long-term consequences of adverse events present during the brain development. At the cellular level, remodeling of the actin cytoskeleton is considered as one of the critical factors associated with the autism spectrum disorders. Alterations in the composition of the neuronal cytoskeleton, in particular abnormalities in the polymerization of actin filaments and their associated proteins underlie the functional consequences in behavior resulting in symptoms and clinical correlates of autism spectrum disorder. In the present review, a special attention is devoted to the role of oxytocin in experimental models of neurodevelopmental disorders manifesting alterations in neuronal morphology.
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133
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Ueda HR, Ertürk A, Chung K, Gradinaru V, Chédotal A, Tomancak P, Keller PJ. Tissue clearing and its applications in neuroscience. Nat Rev Neurosci 2020; 21:61-79. [PMID: 31896771 PMCID: PMC8121164 DOI: 10.1038/s41583-019-0250-1] [Citation(s) in RCA: 300] [Impact Index Per Article: 75.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2019] [Indexed: 02/06/2023]
Abstract
State-of-the-art tissue-clearing methods provide subcellular-level optical access to intact tissues from individual organs and even to some entire mammals. When combined with light-sheet microscopy and automated approaches to image analysis, existing tissue-clearing methods can speed up and may reduce the cost of conventional histology by several orders of magnitude. In addition, tissue-clearing chemistry allows whole-organ antibody labelling, which can be applied even to thick human tissues. By combining the most powerful labelling, clearing, imaging and data-analysis tools, scientists are extracting structural and functional cellular and subcellular information on complex mammalian bodies and large human specimens at an accelerated pace. The rapid generation of terabyte-scale imaging data furthermore creates a high demand for efficient computational approaches that tackle challenges in large-scale data analysis and management. In this Review, we discuss how tissue-clearing methods could provide an unbiased, system-level view of mammalian bodies and human specimens and discuss future opportunities for the use of these methods in human neuroscience.
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Affiliation(s)
- Hiroki R Ueda
- Department of Systems Pharmacology, University of Tokyo, Tokyo, Japan.
- Laboratory for Synthetic Biology, RIKEN BDR, Suita, Japan.
| | - Ali Ertürk
- Institute for Stroke and Dementia Research, Klinikum der Universität München, Ludwig-Maximilian University of Munich, Munich, Germany
- Institute of Tissue Engineering and Regenerative Medicine, Helmholtz Zentrum München, Neuherberg, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Kwanghun Chung
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- Eli & Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Center for NanoMedicine, Institute for Basic Science, Seoul, Republic of Korea
- Graduate Program of Nano Biomedical Engineering, Yonsei-IBS Institute, Yonsei University, Seoul, Republic of Korea
| | - Viviana Gradinaru
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Alain Chédotal
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Pavel Tomancak
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- IT4Innovations, Technical University of Ostrava, Ostrava, Czech Republic
| | - Philipp J Keller
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
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134
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Luo J, Hong B, Jiang Y, Li L, Xie Q, Han H. Automatic Classification for the Type of Multiple Synapse Based on Deep Learning. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:40-43. [PMID: 31945840 DOI: 10.1109/embc.2019.8856509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent studies have shown that the synaptic plasticity induced by development and learning can promote the formation of multiple synapse. With the rapid development of electron microscopy (EM) technology, we can closely observe the multiple synapse structure with high resolution. Although the multiple synapse has been widely researched by recent researchers, the classification accuracy for the type of multiple synapse has not been documented. In this paper, we propose an effective automatic classification method for the type of multiple synapse. The main steps are summarized as three parts: synaptic cleft segmentation, vesicle band segmentation, multiple synapse classification. The experiments on four datasets demonstrate that the proposed method can reach an average accuracy about 97%.
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135
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Badawi Y, Nishimune H. Super-resolution microscopy for analyzing neuromuscular junctions and synapses. Neurosci Lett 2020; 715:134644. [PMID: 31765730 PMCID: PMC6937598 DOI: 10.1016/j.neulet.2019.134644] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/20/2019] [Accepted: 11/21/2019] [Indexed: 12/12/2022]
Abstract
Super-resolution microscopy techniques offer subdiffraction limited resolution that is two- to ten-fold improved compared to that offered by conventional confocal microscopy. This breakthrough in resolution for light microscopy has contributed to new findings in neuroscience and synapse biology. This review will focus on the Structured Illumination Microscopy (SIM), Stimulated emission depletion (STED) microscopy, and Stochastic optical reconstruction microscopy (STORM) / Single molecule localization microscopy (SMLM) techniques and compare them for the better understanding of their differences and their suitability for the analysis of synapse biology. In addition, we will discuss a few practical aspects of these microscopic techniques, including resolution, image acquisition speed, multicolor capability, and other advantages and disadvantages. Tips for the improvement of microscopy will be introduced; for example, information resources for recommended dyes, the limitations of multicolor analysis, and capabilities for live imaging. In addition, we will summarize how super-resolution microscopy has been used for analyses of neuromuscular junctions and synapses.
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Affiliation(s)
- Yomna Badawi
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, 66160, USA
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS, 66160, USA.
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136
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Bucher M, Fanutza T, Mikhaylova M. Cytoskeletal makeup of the synapse: Shaft versus spine. Cytoskeleton (Hoboken) 2019; 77:55-64. [PMID: 31762205 DOI: 10.1002/cm.21583] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/20/2019] [Accepted: 11/21/2019] [Indexed: 12/13/2022]
Abstract
The ability of neurons to communicate and store information depends on the activity of synapses which can be located on small protrusions (dendritic spines) or directly on the dendritic shaft. The formation, plasticity, and stability of synapses are regulated by the neuronal cytoskeleton. Actin filaments together with microtubules, neurofilaments, septins, and scaffolding proteins orchestrate the structural organization of both shaft and spine synapses, enabling their efficacy in response to synaptic activation. Synapses critically depend on several factors, which are also mediated by the cytoskeleton, including transport and delivery of proteins from the soma, protein synthesis, as well as surface diffusion of membrane proteins. In this minireview, we focus on recent progress made in the field of cytoskeletal elements of the postsynapse and discuss the differences and similarities between synapses located in the spines versus dendritic shaft.
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Affiliation(s)
- Michael Bucher
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tomas Fanutza
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marina Mikhaylova
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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137
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Of Molecules and Mechanisms. J Neurosci 2019; 40:81-88. [PMID: 31630114 DOI: 10.1523/jneurosci.0743-19.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 08/25/2019] [Accepted: 08/31/2019] [Indexed: 11/21/2022] Open
Abstract
Without question, molecular biology drives modern neuroscience. The past 50 years has been nothing short of revolutionary as key findings have moved the field from correlation toward causation. Most obvious are the discoveries and strategies that have been used to build tools for visualizing circuits, measuring activity, and regulating behavior. Less flashy, but arguably as important are the myriad investigations uncovering the actions of single molecules, macromolecular structures, and integrated machines that serve as the basis for constructing cellular and signaling pathways identified in wide-scale gene or RNA studies and for feeding data into informational networks used in systems biology. This review follows the pathways that were opened in neuroscience by major discoveries and set the stage for the next 50 years.
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138
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Linking Nanoscale Dynamics of AMPA Receptor Organization to Plasticity of Excitatory Synapses and Learning. J Neurosci 2019; 38:9318-9329. [PMID: 30381423 DOI: 10.1523/jneurosci.2119-18.2018] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/21/2018] [Accepted: 09/21/2018] [Indexed: 11/21/2022] Open
Abstract
The spatiotemporal organization of neurotransmitter receptors in the postsynaptic membrane is a fundamental determinant of synaptic transmission and thus of information processing by the brain. The ionotropic AMPA subtype of glutamate receptors (AMPARs) mediate fast excitatory synaptic transmission in the CNS. The number of AMPARs located en face presynaptic glutamate release sites sets the efficacy of synaptic transmission. Understanding how this number is set and regulated has been the topic of intense research in the last two decades. We showed that AMPARs are not stable in the synapse as initially thought. They continuously enter and exit the postsynaptic density by lateral diffusion, and they exchange between the neuronal surface and intracellular compartments by endocytosis and exocytosis at extrasynaptic sites. Regulation of these various trafficking pathways has emerged as a key mechanism for activity-dependent plasticity of synaptic transmission, a process important for learning and memory. I here present my view of these findings. In particular, the advent of super-resolution microscopy and single-molecule tracking has helped to uncover the intricacy of AMPARs' dynamic organization at the nanoscale. In addition, AMPAR surface diffusion is highly regulated by a variety of factors, including neuronal activity, stress hormones, and neurodegeneration, suggesting that AMPAR diffusion-trapping may play a central role in synapse function. Using innovative tools to understand further the link between receptor dynamics and synapse plasticity is now unveiling new molecular mechanisms of learning. Modifying AMPAR dynamics may emerge as a new target to correct synapse dysfunction in the diseased brain.
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139
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Cuentas-Condori A, Mulcahy B, He S, Palumbos S, Zhen M, Miller DM. C. elegans neurons have functional dendritic spines. eLife 2019; 8:e47918. [PMID: 31584430 PMCID: PMC6802951 DOI: 10.7554/elife.47918] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 10/03/2019] [Indexed: 12/15/2022] Open
Abstract
Dendritic spines are specialized postsynaptic structures that transduce presynaptic signals, are regulated by neural activity and correlated with learning and memory. Most studies of spine function have focused on the mammalian nervous system. However, spine-like protrusions have been reported in C. elegans (Philbrook et al., 2018), suggesting that the experimental advantages of smaller model organisms could be exploited to study the biology of dendritic spines. Here, we used super-resolution microscopy, electron microscopy, live-cell imaging and genetics to show that C. elegans motor neurons have functional dendritic spines that: (1) are structurally defined by a dynamic actin cytoskeleton; (2) appose presynaptic dense projections; (3) localize ER and ribosomes; (4) display calcium transients triggered by presynaptic activity and propagated by internal Ca++ stores; (5) respond to activity-dependent signals that regulate spine density. These studies provide a solid foundation for a new experimental paradigm that exploits the power of C. elegans genetics and live-cell imaging for fundamental studies of dendritic spine morphogenesis and function.
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Affiliation(s)
| | - Ben Mulcahy
- Lunenfeld-Tanenbaum Research InstituteUniversity of TorontoTorontoCanada
| | - Siwei He
- Neuroscience ProgramVanderbilt UniversityNashvilleUnited States
| | - Sierra Palumbos
- Neuroscience ProgramVanderbilt UniversityNashvilleUnited States
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research InstituteUniversity of TorontoTorontoCanada
| | - David M Miller
- Department of Cell and Developmental BiologyVanderbilt UniversityNashvilleUnited States
- Neuroscience ProgramVanderbilt UniversityNashvilleUnited States
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140
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Skallberg A, Bunnfors K, Brommesson C, Uvdal K. Neutrophils Activated by Nanoparticles and Formation of Neutrophil Extracellular Traps: Work Function Mapping and Element Specific Imaging. Anal Chem 2019; 91:13514-13520. [DOI: 10.1021/acs.analchem.9b02579] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- A. Skallberg
- Department of Physics, Chemistry and Biology (IFM), Division of Molecular Surface Physics and Nano Science, Linköping University, Linköping SE-581 83, Sweden
| | - K. Bunnfors
- Department of Physics, Chemistry and Biology (IFM), Division of Molecular Surface Physics and Nano Science, Linköping University, Linköping SE-581 83, Sweden
| | - C. Brommesson
- Department of Physics, Chemistry and Biology (IFM), Division of Molecular Surface Physics and Nano Science, Linköping University, Linköping SE-581 83, Sweden
| | - K. Uvdal
- Department of Physics, Chemistry and Biology (IFM), Division of Molecular Surface Physics and Nano Science, Linköping University, Linköping SE-581 83, Sweden
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141
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Distinct Nanoscale Calcium Channel and Synaptic Vesicle Topographies Contribute to the Diversity of Synaptic Function. Neuron 2019; 104:693-710.e9. [PMID: 31558350 DOI: 10.1016/j.neuron.2019.08.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 05/31/2019] [Accepted: 08/08/2019] [Indexed: 12/22/2022]
Abstract
The nanoscale topographical arrangement of voltage-gated calcium channels (VGCC) and synaptic vesicles (SVs) determines synaptic strength and plasticity, but whether distinct spatial distributions underpin diversity of synaptic function is unknown. We performed single bouton Ca2+ imaging, Ca2+ chelator competition, immunogold electron microscopic (EM) localization of VGCCs and the active zone (AZ) protein Munc13-1, at two cerebellar synapses. Unexpectedly, we found that weak synapses exhibited 3-fold more VGCCs than strong synapses, while the coupling distance was 5-fold longer. Reaction-diffusion modeling could explain both functional and structural data with two strikingly different nanotopographical motifs: strong synapses are composed of SVs that are tightly coupled (∼10 nm) to VGCC clusters, whereas at weak synapses VGCCs were excluded from the vicinity (∼50 nm) of docked vesicles. The distinct VGCC-SV topographical motifs also confer differential sensitivity to neuromodulation. Thus, VGCC-SV arrangements are not canonical, and their diversity could underlie functional heterogeneity across CNS synapses.
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142
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Dosemeci A, Tao-Cheng JH, Bakly V, Reese TS. Postsynaptic densities fragment into subcomplexes upon sonication. Mol Brain 2019; 12:72. [PMID: 31439005 PMCID: PMC6704671 DOI: 10.1186/s13041-019-0491-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 08/09/2019] [Indexed: 11/23/2022] Open
Abstract
Postsynaptic density (PSD) fractions were isolated from rat forebrain and sonicated. Pellets from sonicated samples examined by electron microscopy revealed particles with an electron density similar to PSDs that appeared to be fragments of PSDs. Immuno-gold labeling confirmed that some of these contained PSD-95 and/or SynGAP. Biochemical analysis of supernatant and pellet fractions from sonicated samples showed almost complete recovery of several major PSD components (SynGAP, PSD-95, Shank3, Homer and Glutamate receptors) in the pellet, while the supernatant contained known contaminants of PSD fractions, such as glial acidic fibrillary protein and neurofilament protein, as well as actin and α-actinin, indicating susceptibility of these cytoskeletal elements to mechanical disruption. Size distributions of particulate material in control and sonicated samples were clearly different, with particles in the 40–90 nm range observed only in sonicated samples. Fragmentation of the PSD into subcomplexes containing major constituents suggests a patchwork structure consisting of weakly bound modules, that can be readily dissociated from each other through mechanical disruption. Modular organization and weak association between modules would endow the PSD with lateral structural flexibility.
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Affiliation(s)
- Ayse Dosemeci
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Jung-Hwa Tao-Cheng
- EM Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Valerie Bakly
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Thomas S Reese
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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143
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Bloss EB, Hunt DL. Revealing the Synaptic Hodology of Mammalian Neural Circuits With Multiscale Neurocartography. Front Neuroinform 2019; 13:52. [PMID: 31427940 PMCID: PMC6690003 DOI: 10.3389/fninf.2019.00052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 07/02/2019] [Indexed: 11/20/2022] Open
Abstract
The functional features of neural circuits are determined by a combination of properties that range in scale from projections systems across the whole brain to molecular interactions at the synapse. The burgeoning field of neurocartography seeks to map these relevant features of brain structure—spanning a volume ∼20 orders of magnitude—to determine how neural circuits perform computations supporting cognitive function and complex behavior. Recent technological breakthroughs in tissue sample preparation, high-throughput electron microscopy imaging, and automated image analyses have produced the first visualizations of all synaptic connections between neurons of invertebrate model systems. However, the sheer size of the central nervous system in mammals implies that reconstruction of the first full brain maps at synaptic scale may not be feasible for decades. In this review, we outline existing and emerging technologies for neurocartography that complement electron microscopy-based strategies and are beginning to derive some basic organizing principles of circuit hodology at the mesoscale, microscale, and nanoscale. Specifically, we discuss how a host of light microscopy techniques including array tomography have been utilized to determine both long-range and subcellular organizing principles of synaptic connectivity. In addition, we discuss how new techniques, such as two-photon serial tomography of the entire mouse brain, have become attractive approaches to dissect the potential connectivity of defined cell types. Ultimately, principles derived from these techniques promise to facilitate a conceptual understanding of how connectomes, and neurocartography in general, can be effectively utilized toward reaching a mechanistic understanding of circuit function.
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Affiliation(s)
- Erik B Bloss
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, United States
| | - David L Hunt
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, United States
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144
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Cell type–specific super-resolution imaging reveals an increase in calcium-permeable AMPA receptors at spinal peptidergic terminals as an anatomical correlate of inflammatory pain. Pain 2019; 160:2641-2650. [DOI: 10.1097/j.pain.0000000000001672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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145
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Trotter JH, Hao J, Maxeiner S, Tsetsenis T, Liu Z, Zhuang X, Südhof TC. Synaptic neurexin-1 assembles into dynamically regulated active zone nanoclusters. J Cell Biol 2019; 218:2677-2698. [PMID: 31262725 PMCID: PMC6683742 DOI: 10.1083/jcb.201812076] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/10/2019] [Accepted: 05/30/2019] [Indexed: 12/04/2022] Open
Abstract
Neurexins are well-characterized presynaptic cell adhesion molecules that engage multifarious postsynaptic ligands and organize diverse synapse properties. However, the precise synaptic localization of neurexins remains enigmatic. Using super-resolution microscopy, we demonstrate that neurexin-1 forms discrete nanoclusters at excitatory synapses, revealing a novel organizational feature of synaptic architecture. Synapses generally contain a single nanocluster that comprises more than four neurexin-1 molecules and that also includes neurexin-2 and/or neurexin-3 isoforms. Moreover, we find that neurexin-1 is physiologically cleaved by ADAM10 similar to its ligand neuroligin-1, with ∼4-6% of neurexin-1 and ∼2-3% of neuroligin-1 present in the adult brain as soluble ectodomain proteins. Blocking ADAM10-mediated neurexin-1 cleavage dramatically increased the synaptic neurexin-1 content, thereby elevating the percentage of Homer1(+) excitatory synapses containing neurexin-1 nanoclusters from 40-50% to ∼80%, and doubling the number of neurexin-1 molecules per nanocluster. Taken together, our results reveal an unexpected nanodomain organization of synapses in which neurexin-1 is assembled into discrete presynaptic nanoclusters that are dynamically regulated via ectodomain cleavage.
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Affiliation(s)
- Justin H Trotter
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Junjie Hao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA
- Department of Physics, Harvard University, Cambridge, MA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA
| | - Stephan Maxeiner
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Theodoros Tsetsenis
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Zhihui Liu
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Xiaowei Zhuang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA
- Department of Physics, Harvard University, Cambridge, MA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
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146
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Yang X, Specht CG. Subsynaptic Domains in Super-Resolution Microscopy: The Treachery of Images. Front Mol Neurosci 2019; 12:161. [PMID: 31312120 PMCID: PMC6614521 DOI: 10.3389/fnmol.2019.00161] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 06/12/2019] [Indexed: 12/13/2022] Open
Abstract
The application of super-resolution optical microscopy to investigating synaptic structures has revealed a highly heterogeneous and variable intra-synaptic organization. Dense subsynaptic protein assemblies named subsynaptic domains or SSDs have been proposed as structural units that regulate the efficacy of neuronal transmission. However, an in-depth characterization of SSDs has been hampered by technical limitations of super-resolution microscopy of synapses, namely the stochasticity of the signals during the imaging procedures and the variability of the synaptic structures. Here, we synthetize the available evidence for the existence of SSDs at central synapses, as well as the possible functional relevance of SSDs. In particular, we discuss the possible regulation of co-transmission at mixed inhibitory synapses as a consequence of the subsynaptic distribution of glycine receptors (GlyRs) and GABAA receptors (GABAARs). LAY ABSTRACT Super-resolution imaging strategies bypass the resolution limit of conventional optical microscopy and have given new insights into the distribution of proteins at synapses in the central nervous system. Neurotransmitter receptors and scaffold proteins appear to occupy specialized locations within synapses that we refer to as subsynaptic domains or SSDs. Interestingly, these SSDs are highly dynamic and their formation seems to be related to the remodeling of synapses during synaptic plasticity. It was also shown that SSDs of pre-and post-synaptic proteins are aligned in so-called nanocolumns, highlighting the role of SSDs in the regulation of synaptic transmission. Despite recent advances, however, the detection of SSDs with super-resolution microscopy remains difficult due to the inherent technical limitations of these approaches that are discussed in this review article.
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Affiliation(s)
- Xiaojuan Yang
- École Normale Supérieure, PSL Research University, CNRS, Inserm, Institute of Biology (IBENS), Paris, France
| | - Christian G Specht
- École Normale Supérieure, PSL Research University, CNRS, Inserm, Institute of Biology (IBENS), Paris, France
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147
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Padmanabhan P, Martínez-Mármol R, Xia D, Götz J, Meunier FA. Frontotemporal dementia mutant Tau promotes aberrant Fyn nanoclustering in hippocampal dendritic spines. eLife 2019; 8:45040. [PMID: 31237563 PMCID: PMC6592683 DOI: 10.7554/elife.45040] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/13/2019] [Indexed: 12/14/2022] Open
Abstract
The Src kinase Fyn plays critical roles in memory formation and Alzheimer’s disease. Its targeting to neuronal dendrites is regulated by Tau via an unknown mechanism. As nanoclustering is essential for efficient signaling, we used single-molecule tracking to characterize the nanoscale distribution of Fyn in mouse hippocampal neurons, and manipulated the expression of Tau to test whether it controls Fyn nanoscale organization. We found that dendritic Fyn exhibits at least three distinct motion states, two of them associated with nanodomains. Fyn mobility decreases in dendrites during neuronal maturation, suggesting a dynamic synaptic reorganization. Removing Tau increases Fyn mobility in dendritic shafts, an effect that is rescued by re-expressing wildtype Tau. By contrast, expression of frontotemporal dementia P301L mutant Tau immobilizes Fyn in dendritic spines, affecting its motion state distribution and nanoclustering. Tau therefore controls the nanoscale organization of Fyn in dendrites, with the pathological Tau P301L mutation potentially contributing to synaptic dysfunction by promoting aberrant Fyn nanoclustering in spines.
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Affiliation(s)
- Pranesh Padmanabhan
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), University of Queensland, Brisbane, Australia
| | - Ramón Martínez-Mármol
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), University of Queensland, Brisbane, Australia
| | - Di Xia
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), University of Queensland, Brisbane, Australia
| | - Jürgen Götz
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), University of Queensland, Brisbane, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), University of Queensland, Brisbane, Australia
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148
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Letellier M, Levet F, Thoumine O, Goda Y. Differential role of pre- and postsynaptic neurons in the activity-dependent control of synaptic strengths across dendrites. PLoS Biol 2019; 17:e2006223. [PMID: 31166943 PMCID: PMC6576792 DOI: 10.1371/journal.pbio.2006223] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/17/2019] [Accepted: 05/17/2019] [Indexed: 01/07/2023] Open
Abstract
Neurons receive a large number of active synaptic inputs from their many presynaptic partners across their dendritic tree. However, little is known about how the strengths of individual synapses are controlled in balance with other synapses to effectively encode information while maintaining network homeostasis. This is in part due to the difficulty in assessing the activity of individual synapses with identified afferent and efferent connections for a synapse population in the brain. Here, to gain insights into the basic cellular rules that drive the activity-dependent spatial distribution of pre- and postsynaptic strengths across incoming axons and dendrites, we combine patch-clamp recordings with live-cell imaging of hippocampal pyramidal neurons in dissociated cultures and organotypic slices. Under basal conditions, both pre- and postsynaptic strengths cluster on single dendritic branches according to the identity of the presynaptic neurons, thus highlighting the ability of single dendritic branches to exhibit input specificity. Stimulating a single presynaptic neuron induces input-specific and dendritic branchwise spatial clustering of presynaptic strengths, which accompanies a widespread multiplicative scaling of postsynaptic strengths in dissociated cultures and heterosynaptic plasticity at distant synapses in organotypic slices. Our study provides evidence for a potential homeostatic mechanism by which the rapid changes in global or distant postsynaptic strengths compensate for input-specific presynaptic plasticity.
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Affiliation(s)
- Mathieu Letellier
- RIKEN Brain Science Institute, Wako, Saitama, Japan
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
- * E-mail: (ML); (YG)
| | - Florian Levet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
- Bordeaux Imaging Center, University of Bordeaux, Bordeaux, France
- Bordeaux Imaging Center, CNRS UMS 3420, Bordeaux, France
- Bordeaux Imaging Center, INSERM US04, Bordeaux, France
| | - Olivier Thoumine
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique (CNRS) UMR 5297, Bordeaux, France
| | - Yukiko Goda
- RIKEN Center for Brain Science, Wako, Saitama, Japan
- * E-mail: (ML); (YG)
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149
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Barberis A. Postsynaptic plasticity of GABAergic synapses. Neuropharmacology 2019; 169:107643. [PMID: 31108109 DOI: 10.1016/j.neuropharm.2019.05.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 12/18/2022]
Abstract
The flexibility of neuronal networks is believed to rely mainly on the plasticity of excitatory synapses. However, like their excitatory counterparts, inhibitory synapses also undergo several forms of synaptic plasticity. This review examines recent advances in the understanding of the molecular mechanisms leading to postsynaptic GABAergic plasticity. Specifically, modulation of GABAA receptor (GABAAR) number at postsynaptic sites plays a key role, with the interaction of GABAARs with the scaffold protein gephyrin and other postsynaptic scaffold/regulatory proteins having particular importance. Our understanding of these molecular interactions are progressing, based on recent insights into the processes of GABAAR lateral diffusion, gephyrin dynamics, and gephyrin nanoscale organization. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Andrea Barberis
- Plasticity of Inhibitory Networks, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, Genova, Italy.
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150
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Yang Y, Lu J, Zuo Y. Changes of Synaptic Structures Associated with Learning, Memory and Diseases. BRAIN SCIENCE ADVANCES 2019. [DOI: 10.26599/bsa.2018.2018.9050012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Synaptic plasticity is widely believed to be the cellular basis of learning and memory. It is influenced by various factors including development, sensory experiences, and brain disorders. Long-term synaptic plasticity is accompanied by protein synthesis and trafficking, leading to structural changes of the synapse. In this review, we focus on the synaptic structural plasticity, which has mainly been studied with in vivo two-photon laser scanning microscopy. We also discuss how a special type of synapses, the multi-contact synapses (including those formed by multi-synaptic boutons and multi-synaptic spines), are associated with experience and learning.
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Affiliation(s)
- Yang Yang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ju Lu
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California 95064, USA
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